The invention relates to a switch box for railway, tramway points, or similar, comprising a group operating the motion of translation of the blades of the switch, and at least one group of linear transmission of the operating motion of the blades, movable means locking the blades in their respective positions of closure, said groups being housed in a box which has substantially the dimensions and the shape of a sleeper and which is fitted in the track in place of and with the function of a sleeper.
At present switch boxes of this type are known.
From WO 94/27853 a switch box of this type is known in which, however, only the operating groups the groups of linear transmission of the operating motion and the groups locking the blades in the closed positions are located inside the box. At a central slide, housed in the box branch out drive rods to operate the blades which are external to the same. The group locking the blades in the closed position acts on the very slide and not on the blades, while no means are provided allowing kicking of the blades, that is, the disengagement of the same from the locking means, under the action of a preset force which operates on the blades in direction of displacement of the same.
A further switch box of the type described at the beginning is known from the U.S. Pat. No. 4,093,163. In this case, also the link rods to the blades are housed in the box in shape of a sleeper, while neither means of lockswitching, nor means of kicking are provided.
The invention has the purpose to realize a switch box for railway, tramway points, or similar, of the type described at the beginning, in such a way, whereby means are provided in the same suitable to guarantee all of the functions of locking, lockswitching and or kicking of the usual switch boxes all the elements being mobile, with the exception of the blades integrated inside the box shaped like a sleeper, and the same being realized with an extremely simple construction, of reduced dimensions and such to ensure the housing in the defined available volume, as well as of safe and sure operation.
In particular, the invention aims at the realization of a switch box in which movable means of locking the blades in the corresponding position of closure are provided both by the linear transmission unit of the operating motion, as well as directly by the actual blades, all to reach the maximum operational surety and safety of the switch box.
The invention has also the further purpose to realize a switch box of the type described at the beginning that can be used with few modifications also with the so-called english type points.
The invention attains the above mentioned aims with a switch box of the type described at the beginning, in which are provided movable means for locking the blades in the corresponding closed position which are associated with the respective blade and arranged within the box in the area of the same blade and which are brought automatically into the active locking position when the corresponding blade reaches the position of closure, while they are automatically disengaged at the closed position of the opposite blade at the moment the switch box is activated to operate the blade.
The switch box, has means of linear transmission, formed by a saddle, slide or similar which are moved transversally to the track, particularly orthogonally to the same, in the two directions between the two extreme end of stroke positions by a group translating 10 the rotary motion into a linear motion and to which are linked a transmission rod for each of the two blades, while each blade is connected to a lever coupling it to the respective transmisssion rod thanks to corresponding movable means locking the blade in the closed position.
In particular, the coupling levers of the blades corresponding to the transmission rods form said movable locking means of the blades.
In a preferred form of execution, the said levers are oscillating and have a lateral tooth at the extremity opposite to the one of the fulcrum, each lever being coupled with the corresponding blade by a joint which allows the rotation of the oscillating lever around a perpendicular axis, preferably by means of a ball joint or similar, while the lever cooperates with fixed stops of engagement in the area of the blades there being provided between each coupling lever and the corresponding transmission rod means of control of the angular position of the same lever such, that, during the activation of the switch, the coupling levers are brought into position of disengagement by the stationary stops of engagement, before the transfer of the blades takes place and when the position of closure of one of the two blades is reached, the corresponding coupling lever is moved angularly into position of engagement of the tooth of the extremitity behind the corresponding stationary stop with reference to the direction of transfer of the closed blade to the position moving away from the associated rail.
Advantageously, the control means are formed by shaped slots or grooves which form control tracks with which at least one appendix protruding from the facing side of the coupling levers engages.
The axis of oscillation of the levers is foreseen in the area of the locking means to the corresponding blade, while the coupling lever extends itself beyond the blade in direction of the associated rail.
According to a further feature, the coupling levers are moved alternatively from the position of engagement with the stationary stops to the position of disengagement, thanks to a relative motion of the transmission rods with regards to the same in particular in an initial or terminal section of the stroke of operation.
A particularly advantageous form of construction consists of transmission rods with an angled groove in which at least one control pin of the corresponding coupling engages in motion, in combination with a pair of lateral guide walls of the free end section of transmission rods associated with the coupling levers. The angled slot or groove has a section parallel to the mean longitudinal axis of the transmission rods and which is arranged offset laterally beside said mean longitudinal axis, while said section extends itself towards the free extremity of the transmission rods with an inclined section which terminates substantially in the area of the mean longitudinal axis of the transmission rods or, in any case in an intermediate area of the transversal dimension of said rods. The position of the slot and its conformation, as well as the projection of the tooth of the angled levers is dimensioned and fitted in such a way, that in the initial section of the driving stroke, the transmission rods move relativley to the coupling levers as long as the lever in the engaged position which is associated with the blade closed in the start position is brought in position of disengagement from the stop, while the lever in position of disengagement associated with the blade which has to be brought into the position of closure moves from a substantially intermediate position between the two lateral guide walls into the position where it stops with the head of the tooth against the facing lateral guide wall, while the pins protruding from said coupling levers in the area of the tooth and engaged in the angled grooves, position themselves in an intermediate position of the inclined section of said grooves or slots, whereby, the inclinded wall turned in direction of motion of the blades, of each slott becomes, thanks to the limitation of the oscillation of the transmission lever associated with the blade which has to be brought to the position of closure by the lateral guides, the stop surface for driving the corresponding coupling lever together with the rod, while, as soon as the tooth comes out of the lateral guide the lever is free to oscillate further coming to a position of engagement with the front edge of the lateral guide. As a matter of fact, as soon as, the lateral guide wall or walls can no longer limit the oscillation of the coupling levers, the tie that allows the transmission rod to drive the coupling lever is automatically undone.
Advantageously, each transmission rod has a second slot substantially parallel and coincident with the mean longitudinal axis of the transmission rods and in which a pin or similar is seated which is movable along the rectilinear slot or groove and which with regards to the angular motion of the coupling lever is coaxial to the coupling means of the lever of the blade, for instance to a joint at least of the ball type.
According to a further feature of the invention, the transmission rods are carried by a common saddle supported in translatable manner in orthogonal direction to the axis of the track, the said saddle is connected to a drive slide by means of movable coupling means which pass to a position of disengagement of the rod-carrying saddle from the drive slide when the resistance to the translation of the blades and therefore of the rod-carrying slide exceeds a certain preset torque, or when a force is applied in the direction of translation directly on the blades.
In particular the rod-carrying saddle is provided with sliding rollers in a guide integral with the drive slide, the said rollers are supported spring mounted displaceable transversally to their axis, while each roller engages with an inclined plane provided in the rolling walls of the guide for the rod-carrying saddle, two inclined planes being provided, transversal to the sliding direction of the rod-carrying saddle and with inclinations simmetrically opposite each other for each rolling surface, each of these inclined planes is associated with a roller of the rod-carrying saddle.
Advantageously, the rod-carrying saddle is fitted in a upper guide integral with the drive slide orthogonally translatable to the axis of the track, two projections in shape of an isosceles trapezoid which are facing and coincident with each other are provided in the two opposite vertical lateral walls of the guide for the rod-carrying saddle., while the rod- carrying saddle is formed by two carriage springs fixed to each other, with the interposition of the transmission rod, in correspondence with the extrados sides and foreseen at the free section of the rollers revolving around vertical axis, the length of the carriage springs being such, that in the condition of engagement of the rod-carrying saddle and the drive slide, the vertical rollers are provided at the outermost extremity of the corresponding inclined plane in the area of connection to the vertical lateral wall of the guide.
In combination with the above, the invention furthermore foresees movable locking means of the the drive slide in the two end of stroke positions of closure of the one or the other blade.
Said means have advantageously rocker type means of control of disengagement and which are associated with the coupling means of the drive slide to a linear drive actuator, an initial relative stroke of said coupling means of the slide to linear actuator is provided before the mechanical coupling between the two said parts is made, during the said stroke the locking means of the drive slide are brought into condition of disengagement of the same slide.
The invention also relates to a switch box described at the beginning for an english type points, in which the means of locking the blades in position of closure, are only associated with the outermost blades of the four blades provided, while each of the two internal blades is locked in position of closure thanks to a rigid mechanical connection with the external blade which assumes the closed position of the same together with the internal blades.
The invention presents further features and perfectionings which are the subject of the claims below.
The features of the invention and the advantages derived from the same are better prooven by the Is following description of an executive example illustrated as non-limiting claim in the enclosed drawing in where: